Known firearms may be provided with mechanisms that prevent faulty operation of safety equipment, which may impact the operability of a trigger assembly. For example, the hammer of some known firearms includes a control curve section having a cam-like peripheral surface that is concentric to a pivoting axis and/or hammer shaft of the hammer.
Such known firearms may include a release element designed as a rocking arm or lever. Toward a front end of the lever, a trigger bar is positioned. A rear end of the lever may interact with control surfaces and/or a cam area of a safety shaft. The lever is typically mounted between the ends about a pivoting axis that defines a center of rotation. In operation, when the trigger is moved, the lever tilts about the center of rotation to release the hammer from the cocked position. As the front surface of the trigger bar disengages a hammer stop notch of the hammer, the control curve section of the hammer moves relative to and engages the trigger bar to hold the lever in an unlocked position (e.g., a firing position). Generally, the trigger bar acts as a control surface that is urged toward the control curve section of the hammer via a trigger spring. Additionally, the engagement between the trigger bar and the control curve section of the hammer positions the other end of the lever toward and/or into engagement with the safety barrel such that the safety barrel cannot be moved from the unlocked position (e.g., the firing position) to the locked position (e.g., the safety position). As a result, the hammer may freely move between the firing position and the cocked position.
The engagement between the other end of the lever and the safety barrel ensures that the loading process of the firearm is not affected and that the trigger assembly is not damaged during the loading process. However, if the safety shaft were to be moved to the locked position when the hammer is in the firing position, the hammer may damage the trigger assembly and/or the firing mechanism as the hammer returns to the cocked position. The M16 rifle and U.S. Pat. No. 5,713,150 utilize and/or describe a similar known firing/safety mechanism as described above.
Generally, trigger weight is associated with the amount of force required to activate the trigger (e.g., the trigger lug). The trigger weight of the firing unit or trigger device described above may be dependent on several factors such as, the amount of tension that urges the trigger bar toward a catching position (e.g., engaging position) and a frictional force between the hammer stop notch and the front surface of the trigger bar. To disengage the trigger bar from the hammer stop notch, the friction between the opposing surfaces must be overcome. The amount of friction between the opposing surfaces may be associated with an angle of engagement (e.g., active surface direction) of the hammer stop notch relative to the front surface of the trigger bar, the friction coefficient between the opposing surfaces, and the amount of force that presses the hammer stop notch against the trigger bar. The amount of force that presses the hammer stop notch against the trigger bar is associated with the tension of, for example, a hammer spring and the effectiveness of the lever arm (e.g., the effective distance between the hammer stop notch and the pivoting axis of the hammer). Generally, the closer the hammer stop notch is positioned relative to the pivoting axis, the larger the frictional force between the hammer stop notch and the trigger bar becomes.
The lever arm also dictates the required pivoting space of the control curve section within the housing of the firearm. The control curve section may begin adjacent the hammer stop notch and follow relatively close to the pivoting axis if the lever arm is relatively short or follow relatively far from the pivoting axis if the lever arm is relatively long. A relatively high trigger weight of between about 35 and 40 Newton (e.g., 3.5-4 kilopond) may impact shooting accuracy. In contrast, a relatively lower trigger weight of between about 15-20 Newton (1.7-2 kilopond) may have a lesser impact on shooting accuracy.
There are a number possibilities to reduce trigger weight of a firearm. For example, the friction coefficient between the opposing surfaces of the hammer stop notch and the end of the trigger bar may be treated by, for example, sanding, polishing, coating, etc. However, such an approach is relatively costly to implement and due to the high stresses to which these components are exposed, the treatment may not be very durable.
Alternatively, the angle of engagement (e.g., direction toward each other) between the hammer stop notch and the end of the trigger bar may be changed to decrease the amount of engagement between these surfaces (e.g., the tendency of these two surfaces to jam together). However, such an approach may only be implemented if high production precision is maintained, which increases production costs. Additionally, by changing the angle of engagement, the trigger bar may not function as reliability, thereby enabling the hammer to be released if the firearm is subjected to outside forces (e.g., dropping, hits, vibrations, etc.).
Another option is to reduce the trigger tension, which correspondingly decreases the friction force between the opposing surfaces of the hammer stop notch and the end of the trigger bar and decreases the trigger weight. However, decreasing the trigger tension correspondingly decreases the force imparted via the hammer on a firing pin during firing and, thus, in a worst case scenario, cartridges may not be ignited reliably.
The above described options to decrease trigger weight in a precise and reliable manner all require relatively high production precision to maintain the relatively low trigger weight during long periods without complex maintenance.
Another option to change the trigger weight is to vary the effective lever arm. Such an approach enables the designated effective force to be controlled without considerably increasing production cost.